Process control systems typically include various components for controlling various process parameters. For example, a fluid process control system may include a plurality of control valves for controlling flow rate, temperature, and/or pressure of a fluid flowing through the system. The end product is dependent on the accuracy of the control of these parameters, which is, in turn, dependent on the geometry and characteristics of the control valves. Control valves are, for example, specifically designed and selected to provide for particular flow capacities and pressure changes. When these characteristics are compromised, the quality of the end product may be affected.
A control valve typically includes components such as a valve body, a valve trim assembly (e.g., a flow control member, a valve stem, a valve seat), and an actuator assembly configured to operably position the flow control member within the valve body. These components are, however, susceptible to corrosion as process fluid flows through the control valve. Corrosion may, of course, undesirably compromise the characteristics of the control valve, thereby affecting the quality of the end product.
Thus, it is desirable to minimize the corrosion of control valve components, particularly in the context of a valve body, which can be quite large and, as a result, quite costly and cumbersome to repair or replace. As a result, some approaches have been implemented to minimize such undesirable results. One known approach is to manufacture the entire valve body out of a corrosion resistant material; this approach, however, requires a large amount of the corrosion resistant material, which is typically limited in quantity and, thus, quite expensive to obtain. Another known approach is to weld a layer of corrosion resistant material on the internal surfaces of a casted valve body. This approach, however, requires advanced welding equipment and a skilled welder to complete the task. As such, this approach is time intensive and can be quite costly. And, when the valve body has a complex internal profile, welding often leads to imperfections that may affect the characteristics of the control valve.